Well, it makes sense ^^ I've notice that some instructions was disable and I asked myself why, now I have the answer, security purpose ^^
But does that imply that we can play with every other instructions and assume It will be verify and accepted by a miner (with the appropriate fee ofc) ?
Not exactly security purpose.You can still create the custom transactions using say Python but it is less convenient for the miners.Using of short bitcoins addresses will probably a good alternative as described in P2SH workflow. You can call it as an established Standard accepted by all the miners to communicate with the protocols.